Overclocking my iBook G4

Posted 22 November 2010 - 02:59 AM

Jbbrack03

InsanelyMac Protégé

Members

63 posts

I have an old iBook G4 sitting around that I would not mind messing up if this goes wrong (cheap enough to replace the logic board if I do). I only found one guide that shows how to change some resistors on the bottom of the motherboard to change the multiplier. According to the site (in French), it does not increase the heat in your computer (don't ask me why). Here is a copy of the tutorial that I found (translated into English):

Overclocking iBook G4

In this article you will find how to overclock your iBook G4. This applies to all G4 iBooks first and second generation (12 "up to 1.07 GHz, 14" up to 1.2 GHz)

Introduction:

As always, overclocking a machine requires some experience, and is not without risks. You take these risks when you work on the board, but there is no risk of overheating of the processor because we will not touch the CPU voltage. All the actions you perform on your machine are at your own risk. Handling is relatively easy, but everything that follows should be considered for informational purposes only.

Dismantling the iBook:

Access to the area of the motherboard to overclock is relatively easy. Simply remove the back cover of the machine. The iBooks are considered difficult to dismantle, but in this case, there is no need to disassemble everything as in the case of a change in disk drive for example. For information on dismantling, please file www.powerbook-fr.com.

Locating the config PLL:

Once the rear cover removed, the underside of the motherboard is visible. The pattern area is right next to the Broadcom ethernet controller. There are two lines of resistors, one of 8 elements, the other 7.

This is the red area on the photo.

Changing the PLL config:

All iBook G4's have a 133 MHz bus (except for the last model to 1.42 GHz, but this section does not apply to it) It must therefore be amended to change the PLL multiplier that calculates the speed from the CPU bus. This configuration is done using 4 ohm resistors from 0.

Here is the configuration of the PLL, resistors to change are shown in blue. The figure corresponds to the bit of the PLL to configure.

The resistors in yellow should not be changed. All resistors in red must be removed if they are present on your configuration. The other (blue) must be configured to achieve the desired multiplier based on the following table:

1: no resistance, 0: resistance present

You will find that certain values of the multiplier normally present are not applicable, they use a fifth bit PLL config not determined yet.

If you have an iBook 14 "1.2 GHz, and this table does not match, contact me for the correct configuration.

The original config of your machine may also differ from what is shown here, so all configuration must be redone by removing all resistors marked in red.

Anyway, I would like to attempt to overclock my 800 Mhz G4 to the 1533 Mhz that is mentioned in the tutorial (since it doesn't add heat, there shouldn't be an issue). I've never done anything like this, so I'm using this as an opportunity to learn. So I get that I have to remove the blue resistors from the board. What would be the best way to do this? Also, I interpret this tutorial as meaning that according to the table, if a resistor is listed as a "0", you leave on the board, and if it's listed as a "1", then you remove it as well. Am I correct in this assumption? As far as you guys know, is it a simple matter of just removing the correct resistors to achieve this overclock?